Cold, Unfeeling Traits Linked to Distinctive Brain Patterns in Kids with Severe Conduct Problems (2/21/2008)

The callous, unemotional characteristics of some children and adolescents who bully or steal or have other severely disruptive behavior problems may have partial roots in a brain area called the amygdala.

The amygdala responds to distress cues from other people; cues that normally would elicit empathy from observers. But it is less responsive to such cues in youth who have both callous, unemotional characteristics and disruptive behavior problems, report NIMH investigator Abigail Marsh, Ph.D., and colleagues. Results of their research appeared online February 15 in the American Journal of Psychiatry.

Not all youth who have disruptive behavior problems have callous, unemotional characteristics. But in those who do, behavior problems tend to be more severe and persistent, previous studies have shown.

In this study, researchers measured amygdala activity with a technique called fMRI while three groups of 12 youth 10 to 17 years old looked at photos of fearful, angry, or neutral faces. One group had disruptive behavior problems, such as conduct disorder or oppositional defiant disorder (extremely hostile, belligerent disobedience) coupled with callousness. The second group had only attention-deficit/hyperactivity disorder (ADHD). The third group had no mental disorders.

In response to fearful faces - the expression most likely to elicit empathy - those with disruptive behavior problems and callous, unemotional characteristics had less amygdala activity, compared with those in the other two groups. No differences were seen in amygdala response to angry or neutral faces.

Those with disruptive behavior and callous, unemotional characteristics also had less communication between the amygdala and the ventromedial prefrontal cortex, a brain area thought to process fearful expression and moral reasoning, than did those in the comparison groups.

The study adds to evidence that ADHD and callous, unemotional characteristics have different biological roots. Youth with ADHD often share behaviors of those with callous, unemotional characteristics, such as impulsiveness and irresponsibility. Thus, scientists have studied whether ADHD and behavior problems like conduct disorder and oppositional defiant disorder might stem from the same brain pathology. Results of this study suggest otherwise.

Other studies have linked reduced amygdala activity to callous, unemotional characteristics in adults, but the new study appears to be the first to make the connection in children and adolescents. Revealing the biological basis of these traits can help scientists understand how conduct disorder and other illnesses develop and how best to intervene.

Note: This story has been adapted from a news release issued by the National Institute of Mental Health

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